Rent increases as high as 17 percent were approved late Wednesday by the Ventura Port District for about 550 boat slips in the Ventura Harbor, despite pleas from cash-strapped boat owners.

The rent increases at the Ventura West Marina will vary by slip size but average out to 10.4 percent. Last year, rents were raised an average of 7 percent.

The Ventura West Marina allows almost half — 250 — of its 554 slips to be rented to people who live aboard their boats. They pay additional fees ranging from $110 to $255 a month per slip, depending on the number and age of the residents. Those fees also will rise, by $15 to $25 a month.

The increases will take effect Sept. 1.

More than 50 boat owners, many of them retired or working-class "live-aboards," urged Port District commissioners Wednesday to reject the new increases, arguing they threaten the low-cost housing lifestyle that has existed since the Ventura Harbor was first built in the 1960s.

Rent for a 20-foot slip, the smallest, will increase $10 a month, to $220. A 40-footer will rise $44, to $504, and an 80-footer would go up 17 percent, or $184, to $1,264.

Commissioners expressed sympathy Wednesday night but ultimately decided that rising utility and operating expenses and contractual requirements to replace aging facilities justified the increases proposed by the marina, which leases the area from the Port District. Even with the new increases, rents at the Ventura Harbor will be on average lower than those charged at Channel Islands Harbor in Oxnard.

At the Channel Islands Harbor Marina, a 40-foot slip rents for $609 a month. At the Bar Harbor Marina in Marina del Rey, the rent is $580 a month.

"It's hard not to be sensitive to the dialogue," Ventura Harbor General Manager Oscar Peña said today. "But you can't get away from the fact that the rates are still below the average on a county level."

The Ventura West Marina, in the middle of a 50-year lease with the district, plans to spend some $750,000 on improvements to its land and water facilities, Peña said.

The marina, which has two phases set in separate parts of the harbor, is one of the few remaining marinas in the state that allow a high percentage of live-aboards. All are currently occupied in Ventura, and there's a 165-name waiting list, marina officials said.